This response contains troubleshooting procedures designed to locate the cause of an overnight power drain resulting in a dead battery, It assumes the charging system is working.
The first (and easiest) test I run is on the battery.
When you are done using it for the evening, pull the Negative battery cable.
In the morning, re-connect it. If it's dead again, the battery need replacement. This does not necessarily mean you found the problem.
If it starts, the battery is ok. It's time to look for the power drain.
With the ignition off, ensure the systems that should be off actually are off. For example: does the radio still come on? Wipers? Etc.?
In the same vein, has anything new been installed lately?
The next test is a lot more tedious. You will need a test light, needle nose pliers (to pull fuses) and the proper tools to remove the negative battery terminal (again).
- Ignition off
- Remove the cable from the Negative battery terminal
- Hook one end of your test light to the Negative battery post
- Attach the other end to the cable you just removed
- Again, double check connections to recent installations (radio, GPS, etc)
- If it lights up very faintly, this is likely the normal drain of the clock. The brighter the light, the bigger the drain.
- Find your fuse box
- While keeping an eye on the test light, pull the fuses one by one. Replace the one just pulled before going to the next.
- When the light goes out (or dims), you will have narrowed the the problem to a specific system. Check the legend on the fuse box for the offending fuse.
At this point there are too many 'What if's'. Which system has the drain will determine the next steps to be taken.
This procedure will allow you to focus in on the problem area. Let me know what you find out.
Hope this helps
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